Novel optical MEMS pressure sensors incorporating waveguide Bragg gratings on diaphragms

In this paper we present the design and simulations of novel optical MEMS pressure sensor incorporating waveguide Bragg gratings with silicon micromachined diaphragm. The sensor consists of a curved waveguide with two identical waveguide Bragg gratings located on the diaphragm. When pressure is applied on the diaphragm, the pitch of the gratings changes and hence there is a shift in the corresponding Bragg wavelength. As temperature shifts the Bragg wavelength of the two gratings equally, the error due to temperature change on pressure sensitivity is eliminated. Three different configurations of the sensor with circular, square and rectangular diaphragms are studied. Pressure sensitivity is found to be higher for circular diaphragm compared to the other two and hence is better suited for multiplexing.